Thank you for your input! :> It's allowed me to elaborate on some issues I'd only skimmed on previously.

I honestly had not been aware of that problem! I'm glad you informed me. What I think I'll do is, instead of having a 'Call' option, I'll remove it completely and replace it with an item. Possibly a renewable item, but I was thinking some sort of key item. What do you think?

What I had been thinking was that Shadow and Light Pokémon would have very similar issues battle wise. Light Pokémon are also the opposite to shadow in that, opposed to having closed hearts, their emotions run too freely. Light Pokémon would also have a hyper mode, which would have the same drawbacks as its shadow counterpart.

What I'm going to change about the Shadow leveling (and Light, as well) is that they can level, but with each level, they are more likely to disobey the trainer. Kind of like a traded Pokémon. Eventually, it will reach a certain point where the trainer will have to purify the Pokémon, because they would be literally unable to command it. Perhaps they'd even inflict minor damage to the other Pokémon in the team, but I don't know about that yet.

And when their hearts are unlocked, Shadow Pokémon become normal again. You also have to 'unlock the hearts' of Light Pokémon, and they become normal as well.